CN103971941B - Graphene/polyaniline/oxidation tin composite material applied to ultracapacitor and preparation method thereof - Google Patents

Abstract

The invention relates to a graphene/polyaniline/tin oxide composite material applied to supercapacitors, which is formed by compounding graphene, polyaniline and tin oxide, the polyaniline is coated on graphene, and the tin oxide grown on graphene coated with polyaniline. The graphene/polyaniline/tin oxide composite material that the present invention obtains, this structure has fully utilized the effect of each component, has not only utilized the electrical double layer capacitance property of graphene, also has utilized the oxidation of polyaniline and graphene Reduce the electrochemical properties, increase the specific capacitance of graphene-based electrode materials, and the cycle life reaches 5,000 times, which greatly improves the electrochemical performance of graphene-based capacitors, making it more widely used in supercapacitors, solar cells and other fields application prospects.

Description

Graphene/polyaniline/tin oxide composite material and its preparation for supercapacitor preparation method

technical field

The invention relates to a graphene/polyaniline/tin oxide composite material which can be used as an electrode of a supercapacitor and a preparation method thereof.

Background technique

Supercapacitor, a fast charging/discharging energy storage device between ordinary capacitors and secondary batteries, has the characteristics of short charging time, long service life, good temperature characteristics, energy saving and green environmental protection, etc. It is used in military and There are huge application prospects in civilian use. Supercapacitor electrode materials are divided into two categories, one is supercapacitor materials with electric double layer energy storage properties, such materials include carbon materials such as activated carbon, carbon fiber, carbon nanotube (CNT) and graphene sheets, which have The specific capacitance of 10 to 200F/g has a long charge and discharge cycle life, which can reach more than 10,000 times, but the overall specific capacitance is not high; the other type is a pseudocapacitor material with redox characteristics, both inorganic , such as ruthenium oxide, manganese oxide, tin oxide, iron oxide and other materials, and conductive polymer materials, such as polyaniline, polythiophene, polypyrrole, etc., due to their redox characteristics, these materials have a large capacitance, up to The specific capacitance of more than 500F/g, but the disadvantage of this kind of material is that the redox reaction occurs in the material body, resulting in drastic changes in the volume of the material during charging and discharging, and structural defects, which affect the cycle life of the electrode material. Can be around 3000 times. The design of supercapacitor electrode materials is often to combine electric double layer materials and pseudocapacitive materials through appropriate channels, in order to give full play to the advantages of different materials and obtain positive synergy between the two capacitance behaviors to improve the overall comprehensive performance. In addition to the study of binary composites, the ternary composite electrode materials formed of carbon materials, metal oxides and conductive polymers are also receiving more and more attention. In general, ternary composite materials can combine the advantages of a single component, so as to have more superior performance.

Graphene, as a new type of carbon material, has attracted extensive attention in new composite materials due to its good charge transport properties and ultra-high surface area. As a transition metal oxide, SnO ₂ has special application value due to its cheap and environment-friendly characteristics, and is widely used in supercapacitors and lithium-ion batteries. Polyaniline (PANI), as a typical conjugated polymer, obtains electrical conductivity through p-type doping, because of its cheap raw materials, easy synthesis, wide temperature range, good chemical stability, and high pseudocapacitance The advantages of energy storage properties and good redox reversibility have broad application prospects in energy storage materials, secondary batteries and supercapacitors. Therefore, it is a new research idea to design and synthesize ternary composite electrode materials for supercapacitors based on the large specific surface area of graphene and the unique capacitance characteristics of SnO ₂ and PANI.

Hou et al. prepared a ternary composite MnO ₂ /CNT/conductive polymer, and obtained a specific capacitance of 427F/g (NanoLett, 2010,10(7):2727). Also, researchers loaded iron oxide nanoparticles on the surface of graphene Particles, and then polymerized a layer of polyaniline on the surface of the graphene/iron oxide hybrid, the obtained specific capacitance is 638F/g, and the cycle number is 5000 times (J.Mater.Chem., 2012, 22, 16844). However, since the nanoparticles loaded on the surface of graphene are covered by the polyaniline coating layer, the electrochemical effects of each component cannot be fully exerted, resulting in a specific capacitance that is not as high as expected.

Contents of the invention

The technical problem to be solved by the present invention is to provide a graphene/polyaniline/tin oxide composite material and its preparation method for supercapacitors for the above-mentioned deficiencies in the prior art, which improves the electrochemical performance of graphene-based capacitors .

The technical scheme that the present invention adopts for solving the above-mentioned problem is:

A graphene/polyaniline/tin oxide composite material applied to a supercapacitor, which is formed by compounding graphene, polyaniline, and stannous chloride dihydrate, the polyaniline is coated on the graphene, and the oxide Tin grown on graphene coated with polyaniline.

A preparation method for a graphene/polyaniline/tin oxide composite material applied to a supercapacitor, comprising the steps of:

(1) According to the molar ratio of graphite oxide to aniline is 1: (1~10), add aniline monomer and hydrochloric acid to the aqueous solution of graphite oxide, add the initiator solution dropwise while stirring at 0~5°C, add dropwise Continue to stir for 2 to 5 hours after completion, and separate the obtained solid to obtain a composite of polyaniline/graphite oxide;

(2) reducing the composite of polyaniline/graphite oxide with a reducing agent, and then separating the composite of polyaniline/graphene;

(3) According to the molar ratio of graphite oxide and tin ions is 1: (1~20), mix the compound of soluble tin salt and polyaniline/graphene in water, disperse and stir for 1~3 hours, and pour into it Add concentrated ammonia water dropwise while stirring. The molar ratio of ammonia to tin ions in the concentrated ammonia water is (1-8):1. After the addition is completed, continue stirring for 1-3 hours to obtain a suspension; the obtained suspension is placed at 180-200°C The reaction was carried out for 24 hours, and then the solid therein was separated to obtain a graphene/polyaniline/tin oxide composite material.

According to the above scheme, the concentration of the aqueous solution of graphite oxide is 0.1 mol/L, and after mixing the graphite oxide with deionized water, ultrasonically disperse for 30-60 minutes to obtain the aqueous solution of graphite oxide.

According to the above scheme, the initiator can be selected from (NH ₄ ) ₂ S ₂ O ₈ , K ₂ Cr ₂ O ₇ , KIO ₃ , FeCl ₃ , FeCl ₄ , H ₂ O ₂ , Ce(SO ₄ ) ₂ , MnO ₂ , BPO (benzoyl peroxide), of which (NH ₄ ) ₂ SO ₈ is the most commonly used oxidizing agent because it does not contain metal ions, has strong oxidation ability and is convenient for post-treatment. The initiator solution used in the present invention is an ammonium persulfate solution with a concentration of 0.04mol/L, and the molar ratio of ammonium persulfate to aniline is 1:(1～2).

According to the above scheme, the concentration of hydrochloric acid in the aqueous solution of graphite oxide in the step (1) is 0.8-4mol/L; the dropping rate in the step (1) is 0.15mL/s-0.3mL/s.

According to the above scheme, the reducing agent is hydrazine hydrate or sodium borohydride, and the molar ratio of the reducing agent to graphite oxide is (10-100):1. Hydrazine hydrate is used as the reducing agent, preferably 85% in concentration, and sodium borohydride is used as the reducing agent, preferably in an aqueous solution with a concentration of 0.1mol/L.

According to the above scheme, hydrazine hydrate is used for reduction in the step (2), and the reduction condition is reflux at 90° C. to 100° C. for more than 12 hours.

According to said scheme, the add-on of water in step (3) makes the molar concentration of tin salt be 0.05mol/L～0.2mol/L; Described dispersion is ultrasonic dispersion, and the time is 30-60 minute; The time of described stirring is 4-8 hours; the concentration of concentrated ammonia water is 28%, and the dropping rate is 0.15mL/s-0.3mL/s.

According to the above-mentioned scheme, the preparation method of described graphite oxide is: according to the ratio of (1～5g): (0.2～2g): (30～150ml), graphite, sodium nitrate and 98% concentrated sulfuric acid are mixed, stirrer edge Add potassium permanganate while stirring, the mass ratio of potassium permanganate to graphite is (0.2-8): 1, continue stirring for more than 12 hours after adding potassium permanganate; then add deionized water, deionized water The volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1: (0.05-1.5), then add 30% hydrogen peroxide, the volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1: (0.5-15), obtain a yellow suspension, filter or centrifuge The method is to separate the solid and dry it, which is graphite oxide.

The principle of the present invention is: the carboxyl group on the surface of graphite oxide interacts with the amine group on the aniline, the aniline is first adsorbed on the surface of graphite oxide, and then under the action of the initiator, the aniline monomer is triggered, and the polyaniline is coated on the oxidation surface. Graphite surface; then under the action of reducing agent, it is converted into graphene coated with polyaniline; then, the tin ions are adsorbed on the surface of graphene coated with polyaniline by using the complexation of polyaniline amine groups to metal ions , to convert tin ions into tin hydroxide, and load them on the surface of polyaniline-coated graphene. Finally, through hydrothermal reaction, tin hydroxide is decomposed into tin oxide, so as to obtain the surface-loaded tin oxide and polyaniline-coated graphite Graphene, that is, graphene/polyaniline/tin oxide composite material.

Compared with prior art, the beneficial effect of the present invention is:

The present invention uses the action of graphite oxide and aniline monomer to coat polyaniline on the surface of graphene, and then utilizes the amine group on the polyaniline chain to absorb tin ions, and embeds tin oxide on the surface of graphene/polyaniline to obtain graphene/polyaniline Polyaniline/tin oxide composite material, ingeniously conceived. Simultaneously, the graphene/polyaniline/tin oxide composite material that the present invention obtains, this structure has fully utilized the effect of each component, has not only utilized the electrical double layer capacitance property of graphene, also has utilized polyaniline and graphene The redox electrochemical properties increase the specific capacitance of graphene-based electrode materials, and the cycle life reaches 5000 times, which greatly improves the electrochemical performance of graphene-based capacitors, making them useful in supercapacitors, solar cells and other fields. Broader application prospects.

Description of drawings

Fig. 1 is a schematic flow chart of the preparation method of graphene/polyaniline/tin oxide composite material.

Fig. 2 is the XRD spectrum of the graphene/polyaniline/tin oxide composite material of Example 1, wherein PANI is the abbreviation of polyaniline.

Fig. 3a is the transmission electron microscope picture of graphene, Fig. 3b is the transmission electron microscope picture of the composite of polyaniline/graphene, the intermediate product of Example 1, and Fig. 3c is the transmission electron microscope picture of graphene/polyaniline/tin oxide composite material.

detailed description

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the present invention is not limited to the following examples.

Example 1

1. Preparation of graphite oxide: Take flake graphite (1g), sodium nitrate (0.2g) and concentrated sulfuric acid (30ml) into a 1000ml beaker, add potassium permanganate (1g) while stirring with a stirrer, continue after adding Stir for 14h; then add deionized water (100ml) therein, and then add concentration of 30% hydrogen peroxide (10ml), at this moment, the suspension is yellow, and the solid is separated by filtration or centrifugation, and dried, namely It is graphite oxide, ready for use.

2. A graphene/polyaniline/tin oxide composite material applied to supercapacitors, which is composed of graphene, polyaniline, and tin oxide. The polyaniline is coated on graphene, and the tin oxide grows on graphene coated with polyaniline.

3. A method for preparing a graphene/polyaniline/tin oxide composite material applied to a supercapacitor, comprising the steps of:

(1) Graphite oxide (0.005mol) was ultrasonically dispersed in deionized water (50ml) for 30 minutes, to which aniline monomer was added (the molar ratio of aniline monomer to graphite oxide was 1:1) and 4ml concentrated hydrochloric acid, and then Add dropwise 0.04mol/mL ammonium persulfate solution (the molar ratio of ammonium persulfate to aniline monomer is 1:1) under ice bath while magnetically stirring, and the dropping rate is 0.15mL/s. Stir for 2 hours, then centrifuge the solid therein to obtain a composite of polyaniline/graphite oxide;

(2) Mix all the polyaniline/graphite oxide composites obtained above with hydrazine hydrate (0.05mol), reflux at 90°C for 12 hours, and separate the solids by filtration to obtain polyaniline/graphene composites ;

(3) The compound of polyaniline/graphene and stannous chloride dihydrate powder (wherein the molar number of tin ions is 0.005mol, and the molar ratio of graphite oxide is 1:1) are added into deionized water (100ml ) and ultrasonically dispersed for 1 hour, then stirred for 4 hours, then added dropwise concentrated ammonia water (the molar ratio of ammonia and tin ions in concentrated ammonia water was 1:1) while stirring, and the rate of addition was 0.15mL/s; After completion, the stirring was continued for 1 hour, and the suspension was placed in a reaction kettle to react at 180° C. for 24 hours to obtain a graphene/polyaniline/tin oxide composite material.

According to Figure 2 and Figure 3, it can be seen that the graphene/polyaniline/tin oxide ternary composite system is successfully prepared by this method, polyaniline is grafted and coated on graphene, and tin oxide grows on graphene sheets. It will give full play to the role of each component, so that the specific capacitance of the composite material will be greatly improved, and its specific capacitance can reach 700F/g, charge and discharge 5000 times, and the specific capacitance retention rate is as high as 88%.

Example 2

1. Preparation of graphite oxide: Take flake graphite (1g), sodium nitrate (0.2g) and concentrated sulfuric acid (30ml) into a 1000ml beaker, add potassium permanganate (1g) while stirring with a stirrer, continue after adding Stir for 14h; then add deionized water (100ml) therein, and then add concentration of 30% hydrogen peroxide (10ml), at this moment, the suspension is yellow, and the solid is separated by filtration or centrifugation, and dried, namely It is graphite oxide, ready for use.

2. A graphene/polyaniline/tin oxide composite material applied to supercapacitors, which is composed of graphene, polyaniline, and tin oxide. The polyaniline is coated on graphene, and the tin oxide grows on graphene coated with polyaniline.

3. A method for preparing a graphene/polyaniline/tin oxide composite material applied to a supercapacitor, comprising the steps of:

(1) Graphite oxide (0.005mol) was ultrasonically dispersed in deionized water (50ml) for 30 minutes, to which aniline monomer was added (the molar ratio of aniline monomer to graphite oxide was 10:1) and 16ml concentrated hydrochloric acid, and then Add dropwise 0.04mol/mL ammonium persulfate solution (the molar ratio of ammonium persulfate to aniline monomer is 1:2) under ice bath while magnetically stirring, and the dropping rate is 0.3mL/s. Continue to stir for 5 hours, and then centrifuge the solid therein to obtain the composite of polyaniline/graphite oxide;

(2) Mix all the polyaniline/graphite oxide composites obtained above with hydrazine hydrate (0.05mol, the molar ratio of hydrazine hydrate to graphite oxide is 10:1), reflux at 100°C for 14 hours, and remove the solid Filter and separate to obtain a composite of polyaniline/graphene;

(3) The composite of polyaniline/graphene and stannous chloride dihydrate (wherein the tin ion molar number is 0.1mol, and the graphite oxide molar ratio of feeding is 20:1) joins deionized water (100ml) And ultrasonically dispersed for 3 hours, stirred for another 3 hours, then added dropwise concentrated ammonia water (the molar ratio of ammonia to tin ions in concentrated ammonia water was 4:1) while stirring, and the dropping speed was 0.15mL/s; After that, the stirring was continued for 1 hour, and the suspension was placed in a reaction kettle to react at 190° C. for 24 hours to obtain a graphene/polyaniline/tin oxide composite material.

The specific capacitance of the obtained graphene/polyaniline/tin oxide composite material can reach 900 F/g, charge and discharge 5000 times, and the retention rate of the specific capacitance is as high as 80%.

Example 3

1. Put flake graphite (3g), sodium nitrate (1.1g) and concentrated sulfuric acid (90ml) into a 1000ml beaker, add potassium permanganate (4.5g) while stirring in a stirrer, and continue stirring for more than 12 hours after adding; Add deionized water (350ml) thereto again, then add concentration and be 30% hydrogen peroxide (35ml), this moment suspension liquid is yellow, adopts the method for filtration or centrifugation, solid is separated, dry and stand-by.

2. A graphene/polyaniline/tin oxide composite material applied to supercapacitors, which is composed of graphene, polyaniline, and tin oxide. The polyaniline is coated on graphene, and the tin oxide grows on graphene coated with polyaniline.

3. A method for preparing a graphene/polyaniline/tin oxide composite material applied to a supercapacitor, comprising the steps of:

(1) Graphite oxide (0.005mol) was ultrasonically dispersed in deionized water (50ml) for 30 minutes, to which aniline monomer was added (the molar ratio of aniline monomer to graphite oxide was 5:1) and 8ml concentrated hydrochloric acid, and then Add dropwise 0.04mol/mL ammonium persulfate solution (the molar ratio of ammonium persulfate to aniline monomer is 1:1) under ice bath with magnetic stirring, and the dropping rate is 0.2mL/s. Continue stirring for 3 hours, and then centrifuge the solid therein to obtain a composite of polyaniline/graphite oxide;

(2) Mix all the polyaniline/graphite oxide composites obtained above with hydrazine hydrate (0.025mol, the molar ratio of hydrazine hydrate to graphite oxide is 5:1), reflux at 100°C for 16 hours, and remove the solid Filter and separate to obtain a composite of polyaniline/graphene;

(3) The compound of polyaniline/graphene and stannous chloride dihydrate powder (wherein the tin ion molar number is 0.05mol, and the graphite oxide molar ratio of feeding is 10:1) joins deionized water (100ml ) and ultrasonically dispersed for 3 hours, then stirred for 3 hours, then added dropwise concentrated ammonia water (the molar ratio of ammonia and tin ions in concentrated ammonia water was 2:1) while stirring, and the rate of addition was 0.2mL/s; After the completion, the stirring was continued for 1 hour, and the suspension was placed in a reactor at 200° C. for 24 hours to react to obtain a graphene/polyaniline/tin oxide composite material.

The specific capacitance of the obtained graphene/polyaniline/tin oxide composite material can reach 750 F/g, charge and discharge 5000 times, and the retention rate of the specific capacitance is as high as 85%.

application test

Graphene/polyaniline/tin oxide composite material prepared by the present invention is carried out performance test as electrode material, and concrete test method is: Graphene/polyaniline/tin oxide composite material, acetylene black and polytetrafluoroethylene emulsion (by mass Ratio 80:15:5) mixed into colloid and adhered to nickel foam, with 1mol/L sodium sulfate as electrolyte, cyclic voltammetry and charge and discharge tests were carried out on Shanghai Huachen Electrochemical Workstation, and the test data See Table 1.

Table 1

Wherein, the preparation method of graphene is a conventional preparation method: the graphite oxide used in the present invention is reduced with hydrazine hydrate. The preparation method of graphene/polyaniline is referring to the preparation method step 2 (2) in the embodiment 2 of the present invention.

Comparative example: using graphene and graphene/polyaniline composite as a comparison, the results are shown in Table 1. It can be seen from Table 1 that the obtained graphene/polyaniline/tin oxide composite material not only utilizes the electric double layer capacitance properties of graphene, but also utilizes the redox electrochemical properties of polyaniline and graphene, and increases the size of the graphene-based electrode. The specific capacitance of the material, the cycle life reaches 5000 times, which greatly improves the electrochemical performance of graphene-based capacitors.

Claims (9)

1. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor is characterized in that it comprises the steps: (1) According to the molar ratio of graphite oxide to aniline is 1: (1~10), add aniline monomer and hydrochloric acid to the aqueous solution of graphite oxide, add the initiator solution dropwise while stirring at 0~5°C, add dropwise Continue to stir for 2 to 5 hours after completion, and separate the obtained solid to obtain a composite of polyaniline/graphite oxide; (2) reducing the composite of polyaniline/graphite oxide with a reducing agent, and then separating the composite of polyaniline/graphene; (3) According to the molar ratio of graphite oxide and tin ions is 1: (1~20), mix the compound of soluble tin salt and polyaniline/graphene in water, disperse and stir for 1~3 hours, and pour into it Add concentrated ammonia water dropwise while stirring. The molar ratio of ammonia to tin ions in the concentrated ammonia water is (1-8):1. After the addition is completed, continue stirring for 1-3 hours to obtain a suspension; the obtained suspension is placed at 180-200°C Under reaction for 24h, then the solid therein is separated to obtain the graphene/polyaniline/tin oxide composite material; The graphene/polyaniline/tin oxide composite material applied to supercapacitors is composed of graphene, polyaniline, and stannous chloride dihydrate, the polyaniline is coated on graphene, and the oxide Tin grown on graphene coated with polyaniline. 2. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1 is characterized in that the aqueous solution concentration of graphite oxide is 0.1mol/L, and described graphite oxide and deionized After the water is mixed, ultrasonically disperse for 30-60 minutes to obtain an aqueous solution of graphite oxide. 3. The preparation method of graphene/polyaniline/tin oxide composite material applied to supercapacitor according to claim 1, characterized in that the initiator is selected from (NH ₄ ) ₂ S ₂ O ₈ , K ₂ Cr ₂ One of O ₇ , KIO ₃ , FeCl ₃ , FeCl ₄ , H ₂ O ₂ , Ce(SO ₄ ) ₂ , MnO ₂ , and benzoyl peroxide. 4. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1 or 3 is characterized in that initiator solution is the ammonium persulfate solution of concentration 0.04mol/L, persulfuric acid The molar ratio of ammonium to aniline is 1:(1~2). 5. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1 is characterized in that in the described step (1), the concentration of hydrochloric acid in the aqueous solution of graphite oxide is 0.8～4mol /L; in the step (1), the rate of addition is 0.15mL/s～0.3mL/s. 6. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1 is characterized in that described reducing agent is hydrazine hydrate or sodium borohydride, reducing agent and graphite oxide mol ratio For (10～100):1. 7. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1, it is characterized in that in described step (2) reduction adopts hydrazine hydrate, reduction condition is 90 ℃～100 °C for more than 12 hours. 8. the preparation method of the Graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1, is characterized in that the add-on of water in step (3) makes the molar concentration of tin salt be 0.05mol/ L-0.2mol/L; the dispersion is ultrasonic dispersion, and the time is 30-60 minutes; the dripping rate of concentrated ammonia water is 0.15mL/s-0.3mL/s. 9. the preparation method of the graphene/polyaniline/tin oxide composite material that is applied to supercapacitor according to claim 1, it is characterized in that the preparation method of described graphite oxide is: according to (1～5g): (0.2～ 2g): (30-150ml) ratio, mix graphite, sodium nitrate and 98% concentrated sulfuric acid, add potassium permanganate while stirring in a stirrer, the mass ratio of potassium permanganate and graphite is (0.2-8) : 1, continue to stir for more than 12 hours after potassium permanganate is added; then add deionized water to it, the volume ratio of deionized water to concentrated sulfuric acid is 1: (0.05-1.5), and then add 30% hydrogen peroxide , The volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1: (0.5-15), and a yellow suspension is obtained. The solid is separated by filtration or centrifugation, and dried, which is graphite oxide.